The present invention relates to an improved method for manufacturing decorative plate glass and more particularly, to a method for decorating plate glass wherein crystal ice, e.g., glass powders, is applied to a glass plate where it is melted then rapidly cooled.
Various types of methods for manufacturing decorated plate glass are known in the art in which crystal ice is melted and attached (melt-stuck) to a plate glass in various designs. For example, crystal ice is attached or sprayed onto the surface of plate glass in a desired design, heated in an oven at a temperature of 550xc2x0 C.-630xc2x0 C., depending on the melting point of the crystal ice, for about 40-50 minutes and cooled slowly for about 1-2 hours depending on the thickness and the size of the plate glass.
Such a conventional, decorative plate glass is very beautiful and has artistic merit but suffers from a number of problems associated with the commercialization of the goods:
(1) It is not suitable for mass production and commercialization because it takes too long, e.g., at least 2-3 hours, to produce the product.
(2) During the cooling procedure the crystal ice settles down and loses its shape. Also, cracks are formed in the plate glass as well as in the crystal ice formed on the plate glass.
This phenomenon was noted by the inventor of the present invention during a study of the method of producing decorative plate glass. Thus, when crystal ice 4 is initially heated after it is sprayed or attached to the surface of a plate glass 2xe2x80x2 by placing it into a heating oven as shown in FIG. 1, it is not slowly melted to the melting temperature according to the melting point of the crystal ice 4xe2x80x2, but rather it is melted quickly in a few seconds (FIG. 2). In this procedure, the crystal ice 4 develops surface tension as shown in FIGS. 3 and 4 and pulls on itself, and coheres together on the surface of the plate glass 2xe2x80x2 like a vapor drop, with some designs 6 being formed as shown in FIG. 4. At this moment, the designs are very beautiful and highly transparent.
However, as time passes, the coherent design 6xe2x80x2 slowly spreads out in the sidewise direction, and accordingly, the design 6xe2x80x2 becomes distorted and loses its transparency. Therefore, in the conventional manufacturing method, the shape of the design 6xe2x80x2 on the plate glass 2xe2x80x2 and transparency thereof have not been satisfactory because cooling was not effected using the peak point phenomenon, i.e., the peak point at where the crystal ice melts.
Also, cracks 8, which deal a fatal blow to the strength of the plate glass appeared in the slow cooling procedure of the heated plate glass 2xe2x80x2 as in FIG. 5. This is due to the difference in the coefficient of contraction between the crystal ice 4 and plate glass 2xe2x80x2 when the completely heated plate glass 2xe2x80x2 is slowly cooled.
As shown in FIG. 6, when the melt design 6xe2x80x2 of the crystal ice 4xe2x80x2 and plate glass 2xe2x80x2 are slowly cooled, cracks 8 appears in the plate glass 2xe2x80x2 and in the design 6 because of their different coefficient of contraction. Such cracks 8 reduce the strength of the plate glass 2xe2x80x2, and this phenomenon is affected differently by the thickness of the original plate glass and the cooling time of the plate glass in the processing steps.
The following Table I shows the state in which cracks 8 penetrate into the plate glass 2.
As shown above in Table I, the penetrating ratio and cooling time of the plate glass 2xe2x80x2 are inverse, relative to each other. And as the thickness of the glass is increased and the cooling time is increased, the effect of cracks 8 formed in the crystal ice 4xe2x80x2, on the plate glass is minimized.
Comparing the strength of cracked plate glass used for decorative purposes and that of common plate glass, there is a big difference as shown in the following Table II.
Testing method: Drop Test for Impact
Testing standard: KSL 2002
Weight of testing specimen: 1,040 g
Size of testing plate glass: 300 mmxc3x97300 mm
As shown in the above Table II, a plate glass 2xe2x80x2 having a thickness of under 4 mm is not usable because of the cracks 8 which occurred when the crystal ice 4xe2x80x2 was slowly cooled. Even 5 mm plate glass showed only about 20% of the strength of common plate glass. Because of these problems, and though many methods of forming various designs with crystal ice 4xe2x80x2 have been heretofore proposed, there are still many limitations and many difficulties in producing commercially desirable products.
Accordingly, it is an object of the present invention to provide a method for manufacturing decorative plate glass which eliminates the above problems encountered in conventional methods for manufacturing decorative plate glass.
Another object of the present invention is to provide an improved method for manufacturing decorative plate glass comprising the steps of melting crystal ice (glass powder) and causing it to cohere on the surface of a plate glass at a temperature of about 650-680xc2x0 C. for about 5-6 minutes and rapidly cooling the composite to produce an ornamental and non-cracked plate glass.
A further object of the present invention is to provide a method for decorating plate glass comprising the steps of spraying or attaching crystal ice on the plate glass placing the composite into a heating oven where it is heated to the melting temperature of the crystal ice, and then rapidly transferring the composite structure to a cooling device where it is quick cooled at the moment (peak time) when the crystal ice is melted and cohered to the plate glass.
Still another object of the present invention is to provide a method for decorating plate glass which is simple in structure, inexpensive to manufacture, durable in use, and refined in appearance.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiment of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
Briefly described, the present invention is directed to a method for manufacturing a decorative plate glass, comprising the steps of attaching crystal ice to the surface of a plate glass so as not to be separated; placing the plate glass containing the crystal ice into a heating oven; melting and causing the crystal ice to cohere on the surface of the plate glass; and rapidly transferring the composite structure to a cooling device for quick cooling to produce a decorated plate glass without any cracks. Since crystal ice is melted and caused to cohere to the plate glass in a very short time, the overall strength is much improved, saving time and energy in its manufacture and increasing its productivity and commercialization.